diff --git a/src/compression.jl b/src/compression.jl
index cabc3f9..683ab76 100644
--- a/src/compression.jl
+++ b/src/compression.jl
@@ -79,6 +79,9 @@ end
 # -------
 
 function TranscodingStreams.initialize(codec::ZstdCompressor)
+    if codec.cstream.ptr == C_NULL
+        error("codec use after free")
+    end
     code = initialize!(codec.cstream, codec.level)
     if iserror(code)
         zstderror(codec.cstream, code)
@@ -102,6 +105,9 @@ function TranscodingStreams.finalize(codec::ZstdCompressor)
 end
 
 function TranscodingStreams.startproc(codec::ZstdCompressor, mode::Symbol, error::Error)
+    if codec.cstream.ptr == C_NULL
+        error("codec use after free")
+    end
     code = reset!(codec.cstream, 0 #=unknown source size=#)
     if iserror(code)
         error[] = ErrorException("zstd error")
@@ -111,6 +117,9 @@ function TranscodingStreams.startproc(codec::ZstdCompressor, mode::Symbol, error
 end
 
 function TranscodingStreams.process(codec::ZstdCompressor, input::Memory, output::Memory, error::Error)
+    if codec.cstream.ptr == C_NULL
+        error("codec use after free")
+    end
     cstream = codec.cstream
     ibuffer_starting_pos = UInt(0)
     if codec.endOp == LibZstd.ZSTD_e_end &&
diff --git a/src/decompression.jl b/src/decompression.jl
index 765ce2c..e1834a1 100644
--- a/src/decompression.jl
+++ b/src/decompression.jl
@@ -34,6 +34,9 @@ end
 # -------
 
 function TranscodingStreams.initialize(codec::ZstdDecompressor)
+    if codec.dstream.ptr == C_NULL
+        error("codec use after free")
+    end
     code = initialize!(codec.dstream)
     if iserror(code)
         zstderror(codec.dstream, code)
@@ -57,6 +60,9 @@ function TranscodingStreams.finalize(codec::ZstdDecompressor)
 end
 
 function TranscodingStreams.startproc(codec::ZstdDecompressor, mode::Symbol, error::Error)
+    if codec.dstream.ptr == C_NULL
+        error("codec use after free")
+    end
     code = reset!(codec.dstream)
     if iserror(code)
         error[] = ErrorException("zstd error")
@@ -66,6 +72,9 @@ function TranscodingStreams.startproc(codec::ZstdDecompressor, mode::Symbol, err
 end
 
 function TranscodingStreams.process(codec::ZstdDecompressor, input::Memory, output::Memory, error::Error)
+    if codec.dstream.ptr == C_NULL
+        error("codec use after free")
+    end
     dstream = codec.dstream
     dstream.ibuffer.src = input.ptr
     dstream.ibuffer.size = input.size
diff --git a/test/runtests.jl b/test/runtests.jl
index a111d9a..9488ec8 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -156,6 +156,41 @@ include("utils.jl")
         @test CodecZstd.find_decompressed_size(v) == CodecZstd.ZSTD_CONTENTSIZE_ERROR
     end
 
+    @testset "use after free doesn't segfault" begin
+        @testset "$(Codec)" for Codec in (ZstdCompressor, ZstdDecompressor)
+            codec = Codec()
+            TranscodingStreams.initialize(codec)
+            TranscodingStreams.finalize(codec)
+            data = [0x00,0x01]
+            GC.@preserve data let m = TranscodingStreams.Memory(pointer(data), length(data))
+                try
+                    TranscodingStreams.expectedsize(codec, m)
+                catch
+                end
+                try
+                    TranscodingStreams.minoutsize(codec, m)
+                catch
+                end
+                try
+                    TranscodingStreams.initialize(codec)
+                catch
+                end
+                try
+                    TranscodingStreams.startproc(codec, :read, TranscodingStreams.Error())
+                catch
+                end
+                try
+                    TranscodingStreams.process(codec, m, m, TranscodingStreams.Error())
+                catch
+                end
+                try
+                    TranscodingStreams.finalize(codec)
+                catch
+                end
+            end
+        end
+    end
+
     include("compress_endOp.jl")
     include("static_only_tests.jl")
 end